Router: Failed to SMIME Encrypt message on delivery to journalling database

Getting the following error on domino console while journaling the messages.

Router: Failed to SMIME Encrypt message on delivery to journalling database on behalf of CN=Admin/O=: Either no entry was found with a matching Internet Address or a matching entry was found which did not contain a useable I

nternet certificate.

Admin/ is present & correct the error message comes for some MIME messages.

Domino Server Version: R-8.5.1 FP2